Guard for presses and other like machines



May 2, 1933. J. P. UDAL 1,905,778

GUARD FOR PRESSES AND OTHER LIKE MACHINES Filed July 15. 1931 3Sheets-Sheet l EN/a1 ay 1933. J. P. UDAL GUARD FOR PRESSES AND OTHERLIKE MACHINES Filed July 15. 1931 3 SheetsSheet 2 Fig.2

y 1933. J. P. UDAL GUARD FOR PRESSES AND OTHER LIKE MACHINES Filed Ju15. 1951 s Sheets-Sheet 5 Patented May 2, v1933 .Toim mummy when or"SELLY rink; simmers,

i dumronrmssss AND time are ai 'ncifi n med my 15, 19 1, Serial 115.550,563, and a q a; Bgitaii mesa- 211930;

i invention 1 relates tow guards for presses and other like machines,including Stamps and hammers, and has :for its object to provideimproved means for protecting 5 the hands of t the operatives againstaccidental injury.

Guards are already known in which a pair of principal parts are used,one of them being pivoted across the front of the machine- "so that itcan be swung {outwards in the direction of i the operator, whi'lsttheother is pivoted ion the first mention'edfpar t and a is. likewisearranged to be "swung i outwards towards the. operator.'; In one form ofsuch 7 guard both parts: are causedtoswing' con currently in eachoperationfof the pressor other machine, and in another form the mo.

tion is given first tothe second of the above mentioned parts, and,after this has" been 7 moved to the desired extent pboth parts arecaused to move together. It" is, however, a

characteristic feature of such guards that motion isi'given to bothparts in each opera tive movement ofthe, press or the like.

' A "disadvantage of these guards; is,

especially when applied to hih speed maic'hines,*that owing toinertia eects theyare subjected to considerable stresses, and Icon-- sequentl'ythey must to'be' ver well de- 0 signed and constructedhto" Wit'stand theforces tdwhichtheyare subjected; A fur-- ther disadvantage is that theseguards make a considerable movement towards the -oper ator ineachstroke;which is inconvenient,

inthis guard.- Alsoya'scthe number of times the hand of; theoperator isencountered. by

the guard is very small in comparison with v the number "-of--mov ementsgiven: to the guard, the greater partof the workidone in I moving theguard serves nous'eful purpose.

There is need; therefore; for a guard which, whileitperfo'rinsits' main:purpose of re: movin'g the hand from d nger when the normally orilyfas'malr. movement iwhieh' is little imo're than-sufficient to prevent theIrrth'eQthree accompanying sheetsiof ex-f; e

and this movement'is reduced to a; minimum ,while' the e v bracket 2.

necessity aris'esgand consequently in this con dit'ioii makes; aeonsiderable' movement; has i danger zone motion. I The invention c0mpriesthe combination j of a primary guard part pivoted onthefr'naaft r thepress been set in l'novingportion' ofthe machine; the arrangementbeingsuch that normally the secondary part only'is ,moved by theniach'ine the primary part remaining stationary; but in I the evento'fthe opera-torshand being caught betweenthe two parts of theguard,motion is given to: the primary partifrorn thesecOndary part through themedium of the entrappedhand,ifor the purpose of carrying the latter outof danger.=- I

Figure 1 is a' front elevation and Figure c 2 a side' elevation showinginuthe, inner positiona press guard constructed in accord-a an'cewithjthis' invention. Figure 3 is an end View showing the guard in theextended or outer position. i i

In carrying the invention into, efiect as 'shown'in Figures: 1-3, Isecure by means of brackets a atthe frontofth'e machine ona freelypivoted cross-shaft a the upper ends ofa pair of depending side arms bwhich are joined by one or more horizontal bars a. These-form theprimary partrof the guard; The said part is'held in a convenientposition across thelfront of the press or-the like under the action ofazspring d or by gravity, this position being determined byv'theabutment of an adjustable stop an on the shaft a against one of vthebrackets .a. a The primary partof the guard oiily-moves whenthe'necessity arises; Normallyit remains at rest; It will'be seenfromthe drawingsjhatone end of :the. spring bears against the stop wother end is secured to the At a convenient position on the side arms bof the primary part of the .guard'is arrangedanother cross-shaft e, andonthis' are carried a pair of shorter side'iarms f joined b'yhorizonta'lmembers g forming-the sec- 100 ondary part of the guard. This partnormally swings about the axis of the shaft 6. At the lower part of thearms f is provided a horizontal hand striking member h, and also a likemember 1' is arranged across the lower ends of the arms I), the gapbetween these members h, i, being such that any obstruction of thethickness of the operators finger will not allow the secondary part ofthe guard to pass through the primary part and complete its normalmovement. The normal movement of the secondary part of the guard isthrough the aperture in the primary partwhich gives the operator accessto the tools j of the machine. As is usual the moving tool is fixed onthe lower end of the vertical slide of the machine and the fixed tool ismounted on the bed Z.

Motion is given in each operation of the machine to the secondary guardpart through any convenient lever or link mecl1- anism connected to thesecondary guard part and to any suitable part of the machine such as thecrank shaft or plunger. Preferably a crank m is attached to one end ofthe crank shaft n or other convenient rotating shaft, and this isconnected through a link 0 to a pair of interconnected levers p, gfreely mounted on the cross-shaft'a. In the example illustrated thelever p is attached to an extension of the boss of the lever q, the partof the lever 37 which embraces the said extension being split andsecured by a screw 3 The parts p, Q can be adjusted relatively to eachother by releasing the screw y. Motion is taken from the lever g througha link 1" to one of the side arms f of the secondary guard part. Bymounting the levers p, g coaxially with the shaft w an advantage isobtained in that it allows the whole guard to be conveniently adjustedrelatively to the front of the machine. The normal or initial positionof the guard is determined as already mentioned by a stop m, which isadjustably secured to the shaft a and is arranged to abut against one ofthe brackets 2. When it is required to cause the initial position of theguard to be nearer or further from the machine than is shown in thedrawings the stop as is suitably adjusted.

In each action of the machine the secondary guard part is caused toswing relatively to the primary part (which remains stationary) for thepurpose of closing the aperture in the primary part and so preventingaccess of the operators hand to the tools during the active stroke ofthe machine. This action is illustrated by the full and dotted lines inFigure 2. Normally no movement is given to the primary part of the guardand the secondary part-moves between the position indicated by the fulland dotted lines. Should the operators hand be in the way it is caughtbetween the lower horizontal members h i, of the primary and secondaryguard parts. As the hand thus prevents further relative movement of thesaid parts, both parts move together against the action of thecontrolling spring (I or weight, and the hand is carried away from thedangerous position as shown in Figure 3. For normal purposes themovement of the secondary guard part can be a comparatively small one,but when the hand is trapped a large movement of the two guard parts isdesirable, and the various members of the mechanism are advantageouslyproportioned and arranged. in any convenientmanner such as thatillustrated to satisfy thisrequirement. An important feature of thedesign of the guard is the disposition of lever g and link 0' relativeto each other and lever f. The arrangement is such that in the earlypart of the stroke of the guard the first small angular movement of thelever 9 causes a relatively larger angular movement of the lever f,whereas later in the stroke the angular movement of the lever q is verymuch larger than that of the lever f, which at the end of the stroke ishardly moved at all. This result is obtained because the. upper lever gand its link 2" form a toggle, and the angle between is at the maximumat or near the end of the guard movement.

It will be apparent from the foregoing that in guards constructed inaccordance with my invention only the smaller or secondary part of theguard is normally moved in each action of the machine, and the amount ofmovement given to this part is then little more than sufficient toprevent the hand from entering the danger zone while the machine is inmotion. In the event, however, of the hand being in the dangerousposition when the machine is started, the hand itself serves tointerconnect the guard parts and so cause an ample movement to be givento the main guard part for carrying the hand clear from danger. Thelarger part of the guard, therefore, only comes into action when thenecessity arises. The hand is also pulled out for the same reason ifcaught between the secondary part of the guard and the lower die of thetool of the press. As soon as the secondary part encounters anobstruction ofany kind both guard parts move together and risk oftrapping the hand between the secondary part of the guard and a fixedpart of the machine is thereby obviated.

The invention is not limited to the example above described, andsubordinate details can be varied to suit different requirements. Idesire to emphasize, however, that the mechanism shown in theaccompanying drawings is to be preferred as it enables the requiredmotions of the guard parts to be readily obtained in a manner which isconi I claim as new and desire to secure byLeti i veniently applicableto many different forms of existing machines. 7 Having thus described myinvention what ters Patent is In press and like machine guards, thecomblnatlon of a primary guard part, a

cross shaftcarrying the upper end ofthe v 1 said part, controlling meansacting on said partya secondary guard part pivoted on the 1 primarypart, a source of motion, and actuat ing means for transmitting movementto the :secondary part from the source of motion,

said means comprising a'pair' of relatively adjustable interconnectedlevers mounted co- I axially with the cross shaft, a link connecting oneof the levers to the source'of motion, and a linklconnecting the otherlever directly to the secondary part intermediate its upper and lowerends thelatter lever and link forming a toggle for impartingfa largeangular movement to the primary part in the event of the operators handbeing i caught between the two (partsof the guard, substantially'asdescribe r In testimonylwhereofiI have signed my name to thisspecification.

JOHN POUNTNEY UDAL.

